Thanks to the observation of Varzugin [1]}, we have
\(&1-\sum _{j\ne k}C_{w_j}C_{w_k}\left(1-C_{w_k}\right)^{-1}=\left(1-C_{w}\right)\left(1+\sum _{j=1}^{4}C_{w_j}\left(1-C_{w_j}\right)^{-1}\right),\\&1-\sum _{j\ne k}\left(1-C_{w_k}\right)^{-1}C_{w_j}C_{w_k}=\left(1+\sum _{j=1}^{4}C_{w_j}\left(1-C_{w_j}\right)^{-1}\right)\left(1-C_{w}\right).\) 
